Pico-projectors | Looking at the bigger picture | Economist.com

Pico-projectors | Looking at the bigger picture | Economist.com

Pico-projectors | Looking at the bigger picture
Mar 6th 2008
From The Economist print edition

Consumer electronics: How do you fit an enormous screen into a portable device? By using a tiny projector, of course

THE mere mention of the word “projector” conjures up memories for many people of dull lectures in darkened rooms, boring business presentations or tedious holiday slideshows. It is hard to imagine anyone getting excited about the technology. But some people think projectors could be the next cool piece of hardware to be incorporated into mobile phones and other portable devices. As pocket-sized gizmos have become both smaller and more capable in recent years, their tiny screens have become a growing irritation. That is the inevitable price that must be paid for portability, you may think—but now, it seems, there is another way, in the form of a new generation of miniature or “pico”-projector technologies that can display photos, videos, web pages and maps by beaming them onto a nearby wall or table.

“There's a multitude of mobile-phone users worldwide who are tired of squinting at two-inch displays on their devices. They want a bigger-screen experience,” says Alexander Tokman, the boss of Microvision, a company based in Redmond, Washington, which is one of the pioneers of this new technology. Proponents of pico-projectors think they could find their way into phones, hand-held computers, media players, portable games consoles and laptops, all of which would be able to project a high-resolution, panoramic display onto a nearby wall.

The first pico-projectors will probably be small, stand-alone devices that can be plugged into any video source—much smaller and cheaper versions, in other words, of existing desktop projectors. This alone might open up a new market, since it would allow people to carry projectors around with them, such as business people who make lots of presentations or families who want to watch films in their holiday homes. So even before they become small enough to be incorporated into portable devices, pico-projectors are likely to shake up the existing market for projectors, which are also becoming an increasingly popular way to recreate the big-screen cinema experience at home.

It's all done with mirrors
But making projectors much smaller than this will require a switch to completely new technologies. One approach is to use a variation of the mirror-based design, in which the array of mirrors is replaced with a single pinhead-sized mirror, illuminated by laser diodes, which are very bright, compact and controllable light sources. By steering the mirror very precisely so that it projects one pixel at a time and illuminating it using red, green and blue laser diodes that are switched on and off millions of times a second, it is possible to project an entire image.

Microvision showed off its prototype projector, which works on this principle, at the Consumer Electronics Show in Las Vegas in January. It is about the size of a slim mobile phone, can be plugged into a phone, media-player or laptop, and produces images at a resolution of 848 by 480 pixels. One of the great benefits of using laser diodes, says Mr Tokman, is that they do not require any optics to focus the image. That means the image is always sharp, even when projected onto an uneven or curved surface. The prototype can project images as large as 2.5 metres across and can run for 1.5 hours on a single charge. But it is only meant as a demonstration of the technology, says Mr Tokman, and is simply a stepping stone towards embedding projectors into phones, he says.

When squeezing a new feature into a portable device, however, size is not the only constraint. Minimising power consumption is just as important. Mr Tokman says the big mobile-phone manufacturers have set an upper limit on the power consumption of a projector of 1.5 watts. Given a typical phone battery, this would allow a projector to operate for about 2.5 hours, long enough to watch a film. Microvision's prototype consumes about three watts at the moment, but Mr Tokman expects this figure to fall as the internal circuitry is concentrated within a smaller number of dedicated chips.

The first commercial pico-projectors will probably appear in 2009-10, initially as stand-alone devices, and perhaps as plug-in accessories for mobile phones (rather like the plug-in cameras that predated full camera-phones). If they prove popular, projectors could then be incorporated into all kinds of devices. Will they be powered by DLP, single mirrors or holographic diffraction? Consumers will not be bothered by such details—they will be looking at the bigger picture.